Microphone line based detection of headset plug removal

ABSTRACT

Embodiments of the invention include methods, apparatus, systems and means for distinguishing between microphone line signals resulting from: actuation of a microphone button of a headset plugged into a telephone device jack, and removal of the headset plug form the jack. During a telephone call, a first signal can be detected on a microphone line of a headset jack to indicate whether a microphone button of the headset is actuated. Also, while the headset plug is being disconnected from the jack, a transition on the microphone line can be detected, from a second signal indicating that the microphone is being disconnected, to a third signal indicating that the microphone button is actuated. Consequently, to avoid erroneously hanging up a call, transitions to the third signal when removing the plug form the jack can be ignored and the call can be maintained. Other embodiments are also described and claimed.

FIELD

An embodiment of the invention relates to distinguishing between asignal transition indicating actuation of a microphone button of aheadset plugged into a device jack, and a signal transition indicatingremoval of the headset plug from the jack.

BACKGROUND

Portable devices, such as mobile phones (e.g., cell phones), arebecoming increasingly common. These portable devices have grown morecomplex over time, incorporating many features, including, for example,MP3 player capabilities, web browsing capabilities, capabilities ofpersonal digital assistants (PDAs) and the like. Most of these devicesinclude device jacks into which a headset or headphones may be plugged.In some cases, the headsets include, in addition to earphones forlistening to output of the host device, a microphone to provide input tothe host device over a microphone signal line. Such a headset may have apush button switch, (also referred to as a “microphone button”) to senda DC control signal to the host device over the microphone signal line.For example, actuating the switch sends a signal that instructs the hostdevice to disconnect or hang up an ongoing phone call.

SUMMARY

In some cases, a telephone call may be erroneously disconnected by thehost device during removal of a headset plug from the jack, even whenthe user has not actuated the microphone button. This occurs because thehost device incorrectly interprets a signal transition on the microphoneline to be due to actuation of the microphone button, rather than due toremoval of the plug. Such incorrect detection may occur when contacts ofthe plug cause a signal transition from a normal current level to a highcurrent level on the microphone line contact of the jack, while removingthe plug from the jack. This in turn may be due to the jack's groundcontact connecting to the microphone line contact through a lowimpedance connection (e.g., through one or two speakers of a headset).Thus, removing the plug from the jack may result in the erroneousinterpretation by causing two adjacent contacts of the plug toinadvertently connect the jack contacts through a substantially lowerimpedance path than a “normal” path on the microphone line (e.g., lowerthan a path detecting a normal audio signal at the microphone).

To avoid this situation, during a call, embodiments of the invention areable to distinguish between microphone line signal transitions resultingfrom: (1) actuation of the microphone button, and (2) removal of theheadset plug from the jack. To do so, some embodiments of the hostdevice can detect: (1) a transition between a first stable DC level atthe microphone line and a third stable DC level (a transition indicatingthat the microphone button has been actuated); and (2) a transition fromthe first DC level to a second stable DC level and then a transitionfrom the second to the third DC level, where the second level is notbetween the first and the third levels (either of these transitionsindicating that the plug is being removed from the jack). By detectingand then ignoring the signal transitions in (2) above, the call ismaintained, instead of being erroneously disconnected, during removal ofthe plug from the jack.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments are illustrated by way of example and notlimitation in the figures of the accompanying drawings in which likereferences indicate similar elements.

FIG. 1 shows an example of a mobile telephone which includes a headsetjack, and a headset having a headset plug.

FIG. 2 shows an example of a headset jack and headset plug.

FIG. 3 shows an example of a headset jack, a headset plug, andelectronic schematics of some embodiments of headset and mobiletelephone circuitry.

FIG. 4 shows some embodiments of an example of a signal output by themicrophone line when the microphone button is actuated.

FIG. 5A-5C show examples of contact between plug contacts and jackcontacts, and examples of microphone line signals and headphone detectsignals when the plug is being removed from the socket.

FIG. 6 shows an example of circuitry coupled to jack contacts fordistinguishing between receiving a signal transition indicatingactuation of a microphone button of the headset, and a transitionindicating removal of the headset plug from the jack.

FIG. 7 shows some embodiments of an example of a flow diagram of aprocess for distinguishing between receiving a signal transitionindicating actuation of a microphone button, and a transition indicatingremoval of the headset plug from the jack.

FIG. 8 shows some additional embodiments of an example of a flow diagramof a process for distinguishing between receiving a signal transitionindicating actuation of a microphone button, and a transition indicatingremoval of the headset plug from the jack.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Various embodiments and aspects of the inventions will be described withreference to details discussed below, and the accompanying drawings willillustrate the various embodiments. The following description anddrawings are illustrative of embodiments of the invention and are not tobe construed as limiting the invention. Numerous specific details aredescribed to provide a thorough understanding of various embodiments ofthe invention. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the inventions.

To provide a proper and efficient operation of mobile phones, plugdetection mechanisms or circuitry may be used for determining whether aplug is present or has been removed from a jack of the phone. The devicecan be configured to adjust its operation responsive thereto. However,in some portable devices, the plug detection mechanism may detect whenthe plug has been removed after actual physical removal of the plug, orafter erroneous interpretation or detection of a signal transitionresulting from removal of a headset plug from the jack. Thus, in orderfor proper and more efficient device operation, an early plug removaldetection circuit may be used to distinguish between a signal transitionindicating actuation of a microphone button of a headset plugged in adevice jack, and a signal transition received during removal of theheadset plug from the jack.

Hence, the device can be configured to not adjust its operationresponsive to the erroneous transition. For example, during a telephonecall, a transition may be detected at a microphone line of the jack,indicating that a microphone button of a headset has been actuated; anda different signal transition may be detected, indicating that the plugis being removed from the jack. Thus, the phone call may be disconnectedif the first transition is detected, but will be maintained if thedifferent second transition is detected. Consequently, the device willnot erroneously (unintentionally, or inadvertently) hang-up ordisconnect a telephone call during removal of the plug from the jack.Also, in some embodiments, the device will not erroneously hang-up ordisconnect a telephone call even though, during removal of the plug fromthe jack, the microphone contact and the ground contact of the jackinadvertently connect to each other through the substantially lowimpedance path of a headphone speaker (or both speakers). Although thispath is not a direct short to ground, it is substantially lower inimpedance than that of a headphone microphone. Herein, the terms“headset” and “headphone” may be used interchangeably.

FIG. 1 illustrates mobile telephone 100 in accordance with someembodiments of the invention. Phone 100 can have display 102, user inputinterface 104, and external antenna 106. Display 102 can providegraphical information to a user. User input interface 104 can permit auser to input information into phone 100. For example, user inputinterface 104 can include one or more buttons, touchpads, touchscreens,scrollwheels, clickwheels, sliders, other appropriate input mechanism,or combinations thereof. In some embodiments of the invention, display102 and user input interface 104 can be combined, e.g., in a touchscreenor touchsensitive display. In some embodiments, a combined display anduser input interface may occupy at least 60 percent or at least 65percent of one side or surface of phone 100.

Phone 100 also can be equipped with built-in speaker 108, built-inmicrophone 110, and headset jack 112. Built-in speaker 108 can outputaudible sound to a user, while built-in microphone 110 can acceptaudible sound from the user. Headset jack 112 can accept plug 114 fromheadset 116. When headset plug 114 is properly inserted into headsetjack 112, phone 100 can be configured to output audible sound fromearphones 118 rather than speaker 108; and to accept audible sound fromheadset microphone 120 rather than microphone 110. Thus, for someembodiments, phone 100 may be described as a host device, such as a hostto headset 116.

Microphone button 121 of headset 116 can be used (e.g., actuated and/orreleased) to control the output of microphone 120 to phone 100, such asby controlling the signal received at jack 112 from the microphone.Button 121 can also be used to control the behavior of phone 100, suchas by causing the phone to change between two behaviors or actions.Examples of behaviors controlled by button 121, include (but are notlimited to) causing the phone to: (1) turn microphone 120 on and off,(2) cause music files stored in the phone (e.g., MP3 files or the like)to start playing, (3) disconnect a telephone call, and/or (4) initiateor dial a telephone call. Thus, when headset plug 114 is properlyinserted into jack 112, actuating button 121 may cause phone 100 todisconnect an active telephone connection between phone 100 and anothertelephone capable device.

Button 121 may be a microphone button that as known in the art, such asa button that is actuated when a user presses or pushes the button. Itmay be a type of button that locks into an actuated position oncepressed, and has to be pressed again to be released (un-actuated); ormay be a type of button that does not lock but only maintains anactuated position while it is being pressed, and is released once thepressure is removed.

In some embodiments, phone 100 may represent any one or more of thevarious electronic devices having jack 112, as described herein.Similarly, headset 116 may represent one or more accessory componentshaving plug 114, such as also described further below.

FIG. 2 illustrates headset jack 112 and headset plug 114 in greaterdetail in accordance with some embodiments of the invention. Headsetjack 112 can have receptacle 122, within which is disposed one or moreelectrically conductive contacts 124 a-124 d. Headset plug 114 can havecomplementary electrically conductive contacts: microphone signalcontact “M”; ground signal contact “G”; right earphone signal contact“R”; and left earphone signal contact “L”. Each contact 124 a-124 d canbe electrically isolated from adjacent contacts. Likewise, each contactM, G, R, and L also can be electrically isolated from adjacent contacts,such as by insulator rings 123 spaced along the length of plug 122.Insulator rings 123 may be or include one or more non-electricallyconductive materials or insulator between contacts as know in the art.For example, insulator rings 123 may include a thickness of a dielectricmaterial such as a non-conductive polymer, ceramic, plastic and/orrubber.

FIG. 3 shows an example of a headset jack, a headset plug, andelectronic schematics of some embodiments of headset and mobile phonecircuitry. FIG. 3 shows plug 114 completely and properly inserted intoreceptacle 122 of jack 112 (e.g., not partially removed), such thatcontacts 124 a-124 d of host 100 make electrical contact with (e.g.,touch) contacts M, G, R, and L of headset 116, respectively. Contacts124 a and M can transmit (e.g., pass) signals between phone 100 andmicrophone 120 (and button 121) of headset 116. Similarly, contacts 124b and G transmit a ground signal; and contacts 124 c-d and R-L cantransmit audio signals between phone 100 and earphones 118 of headset116. FIG. 3 also shows contacts 124 c and 124 d electrically connectedto right channel amplifier 154 and left channel amplifier 152 of host100, respectively.

These amplifiers may transmit or provide the audio signals to speakers118R and 118L of headset 114, respectively. FIG. 3 also shows contact124 a electrically connected to bias voltage Vmicbias through resistor134 of host 100. When the plug is completely inserted, contacts 124 aand M connect or transmit signal or current “I”, such as a signalcontrolled by Vmicbias, resistor 134, contact 124 a, microphone 120 andswitch 121. Contact 124 a is electrically connected to audio inputcircuit and to early plug removal detection circuit 129. Although notshown in FIG. 3, each of these circuits may detect or measure current I,such as based on a voltage drop across resistor 134, and/or using othercircuitry. Thus, the audio input circuit measures the audio signal ofthe microphone that comes in via this connection. Each contact 124 a-dalso can be assigned to serve other roles, such as for various types ofheadsets. For example, contact 124 d and G can serve as ground and theremaining contacts can transmit signals, as described above.

FIG. 3 shows microphone 120 and button 121 electronically coupled inparallel between ground GND and contact M. Button 121 be a switchelectronically coupled across the input and output of microphone 120.Ground GND may be coupled to ground contact G of the headset plug.Button 121 may be a switch that is normally in the open circuitposition, but when actuated creates a short circuit across the input andoutput of microphone 120, shorting contact M to ground GND. Microphone120 may use a field effect transistor or amplification system to amplifya sensed signal in the audio range, such as from a human voice.

Jack 112 may also include a headphone detect mechanism (not shown, butsuch as circuitry 149 of FIG. 6 and voltage signal VHPDET of FIG. 5). Insome embodiments, one of the functional contacts of jack 112 may be usedto detect whether headset plug 114 is inserted into headset jack 112,using a switch that is actuated when the headset plug is inserted intothe jack. For example, one of contact 124 a, b, c or d can be coupled toan electrical switch that provides headphone detect signal VHPDET.VHPDET may be a voltage pulled-up to the voltage value of a bias orsupply rail that gets short circuited through contact L (e.g., headphoneleft speaker contact) when the plug is inserted. Here, VHPDET will beapproximately zero when not the plug is present P, and a bias voltagevalue when the plug is removed R.

FIG. 4 shows some embodiments of an example of a signal I output bymicrophone contact M electrically connected to microphone button 121when the button is actuated. FIG. 4 shows signal output graph 462plotting the current I versus time. Graph 462 may represent a case wherea bias voltage Vmicbias is applied to contact M from contact 124 a, andcurrent level S1 is a normal output current response for the microphone.Thus, when sensing an audio signal, signal S1 represents a signalconsidered to be “normal” or in a normal range for the output ofmicrophone 120. Alternatively, when button 121 is switched to a shortcircuit, by actuating button 121, short circuit signal S3 is createdbetween contact M and ground, disconnecting the output of microphone 120from contact M.

Thus, graph 462 shows normal current and voltage signal S1 at contact Mwhen button 121 is in its normally open circuit position (e.g., notactuated) prior to time TS. Time TS represents when button 121 istransitioned to a short circuit position, such as by actuating button121. Current I then transitions from S1 to S3. This transition may bedetected at contact 124 a and used by the phone to detect or identifyactuation of button 121. As also shown, at a later time, button 121 maybe released back to its normally open circuit position (e.g., not ornon-actuated), transitioning signal I from S3 to S1.

If during removal of a microphone plug from a jack, a signal received bycontact 124 a is misinterpreted as signal I shown in FIG. 4, anerroneous detection of button actuation may occur. For example, in someembodiments, during plug removal, a microphone line of the jack (e.g., asignal line of phone 100 attached to contact 124 a) may be connected toa substantially lower impedance path than a path on the microphone line,even though the microphone button is not actuated. The resulting signallevels, or a transition detected at contact 124 a may be incorrectlyinterpreted as button actuation if removal of the plug is not yetdetected. Thus, contact 124 a is electrically connected to early plugremoval detection circuit 129 in FIG. 3 to distinguish between signal Iduring plug removal from signal I during button actuation.

More specifically, FIGS. 5A-5C show examples of contact between jackcontacts 124 a-d and plug contacts M, G, R, and L during removal of theplug from the jack. These figures show example locations of the plugwithin the jack during a progression of removal between the plug beingcompletely and properly inserted into jack 112 (e.g., FIG. 3), and theplug being completely removed from jack 112 (e.g., FIG. 2). Removal ofthe plug from the jack may include a portion, but not all of the plugbeing disposed within the jack, such as resulting from a device userpulls the plug out of the jack and/or when the plug is partially, butnot completely removed from the jack.

FIGS. 5A-5C also show signal output graph 562 plotting current I andsignal output graph 564 plotting voltage VHPDET versus time duringremoval of the plug from the jack. In

FIG. 5, microphone line current I may be the signal received by amicrophone line of phone 100 from contact M. When the microphone issensing signals in the audio range, such as from a human voice, theoutput of the microphone may be considered to be in a “normal” range,such as shown by current signal S1. Also, when current I is zero (or themicrophone line has no signal), the output of the microphone may beconsidered to be an open circuit voltage, such as shown signal S2. Next,when current I is substantially greater than S1 (or when the microphoneline is connected to a substantially lower impedance path than a pathwhen sensing signals in the audio range), the output of signal I may besignal S4 or S5. During removal, graph 562 of FIGS. 5A-5C shows periodscorresponding to: (N) when contact 124 a contacts contact M; (GR)contact 124 a contacting contact G, and contact 124 b contacting contactR; (RL) contact 124 a contacting contact R and contact 124 b contactingcontact L; (CR) only contact L or no plug contact contacting contact 124a. FIG. 5 also shows upper current threshold TU between S1 and S4 or S5(or S3); and lower current threshold TL between S1 and S2.

Signal VHPDET may be used by a detect mechanism of host 100 during aprogression described for FIGS. 5A-5C to detect removal of plug 114 fromjack 112. Transitions may be detected by comparing voltage VHPDET tovoltage thresholds TR and TP. For instance, if VHPDET transitions toabove TR, it may be detected that a transition to VR has occurred. Also,if VHPDET transitions to below TP, it may be detected that a transitionto VP has occurred. Thus, times T1-T5; and time prior to time TR defineheadphone detect period P (presence of the plug). Conversely, time aftertime TR defines headphone detect period R (removal of the plug).

According to some embodiments, removal of the plug may not be detectedusing the signal transition of VHPDET at time TR until after atransition or level of current I is misinterpreted as button actuation.For instance, VHPDET may not transition at time TR until after thetransition of signal I from S2 to S4 at time T3 (and optionally, notuntil after the transition S2 to S5 at time T5 as shown in FIG. 5), thusallowing the transition(s) of signal Ito be misinterpreted as buttonactuation transition 51→S3 of FIG. 4. This may occur due to a requiredplacement of conductors of the detect mechanism used to provide signalVHPDET, where the placement of conductors is selected or predeterminedto maintain compatibility across various types of headphone plugs (e.g.,plug 114) for various types of headphone or headset units. To avoidmisinterpreting the signal I transition(s) during plug removal, atransition from signal S1 to S2; or from signal S2 to signal S4 or S5,may be detected.

For example, FIG. 5A shows contact between plug contacts and jackcontacts when plug 114 is just beginning to be removed from or pulledout of jack 112. In this case, contact 124 a is only electricallyconnected to or touching ring 123 of plug 114, and is not in contactwith any adjacent contact of the plug (e.g., is not touching contacts Mor G). Thus, current I may be S2 during the time period between T1 andT2. As shown in FIG. 5A, contact 124 a may be biased towards insulator123 between contact M and G of the plug, causing a transition in signalI from S1 to S2 before any of contact 124 b-d are disconnected fromcontacts G, R and L of the plug.

However, in FIG. 5A a headphone detect mechanism may still be indicatingthe presence of the plug in the jack (e.g. based on signal VHPDET atdetect contact HDC). Although current I transitions from S1 to S2 oncecontact 124 a only contacts ring 123 of plug 114, the headphone detectsignal VHPDET may not have transitioned yet from headphone to headphoneremoved signal VR at time TR.

FIG. 5B shows contact between plug contacts and jack contacts after theplug has been removed further from the jack than is shown in FIG. 5A andbefore FIG. 5C. FIG. 5B shows contact 124 a of jack 112 electricallyconnected to or touching contact G of plug 114, and contact 124 b ofjack 112 electrically connected to or touching contact R of plug 114. Asa result, speaker 118R is electrically connected between adjacentcontacts G and R. According to embodiments, speaker 118R has asubstantially lower impedance path than a path on the microphone headsetline (e.g., through microphone 120 and button 121) when detecting anaudio signal from the microphone during a phone call (e.g., and whilebutton 121 is not activated). Thus, current I may be S4 (current levelIGR), during the time period GR between T3 and T4.

In FIG. 5B a headphone detect mechanism may still be indicating thepresence of the plug in the jack based on signal VHPDET still beingequal present signal VP prior to time TR. Current I transitions from S2to S4 once contact 124 a contacts contact G of plug 114 and contact 124bcontacts contact R. However, VHPDET has not yet transitioned to signalVR at time TR (e.g. may transition too late to avoid misinterpretationof signal S4 based only on VHPDET). Thus, the signal levels and/ortransitions of FIG. 5A-B may be incorrectly interpreted as buttonactuation (signal S1 transition to S3 of FIG. 4) if plug removal isdetected only using VHPDET.

To avoid misinterpreting signal transitions S1→S2→S4 as transition S1→S3of FIG. 4, transition to (or from) S2 prior to signal S4 (and aftersignal S1), may be detected.

After FIG. 5B and prior to FIG. 5C, contact 124 a may transition frombeing electrically connected to or touching contact G of plug 114, toonly being electrically connected to or touching ring 123 of plug 114(e.g., not being in contact with either adjacent contact). Thus, currentI transitions from S4 to S2 once contact 124 a only contacts ring 123.

FIG. 5C shows contact between plug contacts and jack contacts after theplug has been removed further from the jack than is shown in FIG. 5B andbefore complete removal CR. FIG. 5C shows contact 124 a of jack 112electrically connected to or touching contact R of plug 114, and contact124 b of jack 112 electrically connected to or touching contact L ofplug 114. As a result, speakers 118R and 118L are electrically connectedin series between adjacent contacts R and L. According to embodiments,speakers 118R and 118L, in series, have a substantially lower impedancepath than a path on the microphone headset line when detecting an audiosignal from the microphone during a phone call. Thus, current I may beS5 (current level IRL), during the time period RL between T5 and T6. Insome cases, speaker 118R and 118L may each have a resistance between 16and 64 Ohms. Also, in some embodiments, microphone 120 has a resistanceof between approximately 2K and 5.5K Ohms when biased with approximately1 Volt and detecting an audio signal. For instance, the microphone canpull, depending on the type of microphone, typically between 180 μA and500 μA at 1 Volt. It can be appreciated that these values may changedepending on the operating point and/or type of the microphone.

In FIG. 5C a headphone detect mechanism may still be indicating thepresence of the plug in the jack based on signal VHPDET which is stillequal present signal VP as shown in segment P. Current I transitionsfrom S2 to S5 once contact 124 a contacts contact R of plug 114 andcontact 124 b contacts contact L. However, VHPDET has not yettransitioned to signal VR at time TR. Thus, the signal levels and/ortransitions of FIG. 5B-C may be incorrectly interpreted as buttonactuation (signal S1 transition to S3 of FIG. 4) if plug removal isdetected only using VHPDET. To avoid misinterpreting signal transitionsS1→S2→S4→S2→S5 as transition S1→S3 of FIG. 4, transition to (or from) S2prior to signal S5 (and after signal S1), may be detected.

After FIG. 5C, contact 124 b may transition from being electricallyconnected to or touching contact L of plug 114, to being electricallyconnected to or touching none of the contacts of plug 114. For example,current I may transition from S5 to S2 at time T7. Once contact L is nolonger in electrical contact with or touching contact 124 b, current Imay transition from signal S5 to signal S2 and remain at signal S2, suchas until the plug is reinserted in the jack. This occurrence, at time T7and indicate a period of “complete removal” of the plug from the jack asshown by period CR after time T7.

When the plug is not being removed, signal I in FIG. 4 does not include(or excludes) the transition from S1 to S2 as well as the transitionfrom S2 to S4 that result from contact of contact 124 a with ring 123during removal of the plug as shown in FIG. 5. Consequently, detectingthe signal transition from S1 to S2 at time T1, prior to the transitionfrom signal S2 to S4 or S5 distinguishes current I during plug removalfrom current I during button actuation. Also, detecting the transitionfrom S2 to S4 or S5 (at time T3 or T5) may be used to make such adistinction. Likewise, detecting transition to and from S2 prior S4 orS5 may be used to make such a distinction.

FIG. 6 shows an example of circuitry coupled to jack contacts fordistinguishing between receiving a signal transition indicatingactuation of a microphone button of a headset plugged into a devicejack, and a transition indicating removal of the headset plug from thejack. FIG. 6 shows phone 100 including an example of early plug removaldetection circuit 129 and additional plug detect circuitry 149 coupledto control unit 130. Control unit 130 may comprise specialized circuitryfor detecting, interpreting, and changing behavior of phone 100 basedsignal I. In some embodiments, control unit 130 can comprise a CPU,other digital circuitry, analog circuitry, or any combination thereof ofspecialized circuitry for detecting, interpreting, and changing behaviorof phone 100 based on the output of circuit 129 (and optionally circuit149). In some embodiments, control unit 130 and/or phone 100 may includea CODEC, a processor, and/or a signal processor, such as to also processthe audio output of (e.g., audio input to the device from) microphone120.

Current I can be compared to the thresholds TU and TL using early plugremoval detection circuit 129 of FIG. 6 to distinguished signal I duringplug removal as compared to signal I during button actuation.Consequently, based on detecting one or both of the signal transitionsfrom S1 to S2 and/or from S2 to S4, the host device (e.g., device 100)can ignore the total transition starting at S1 and resulting at S4 afterFIG. 5A (eventually, after the transitions to and from S2 between T1 andT3). Thus, a telephone call may be maintained, instead of erroneouslydisconnected during removal of the plug from the jack. Such ignoring ofthe transition from S1 to S4 shown as shown in FIG. 5 may be describedas “early” plug removal detection since it occurs prior to detection ofheadset removal by plug detect circuitry 149 of FIG. 6.

FIG. 6 illustrates additional plug detect circuitry 149 coupled to theheadphone detect contact HDC receiving signal VHPDET for detecting thepresence of a plug in accordance with some embodiments of the invention.Current VHPDET of FIG. 6 may be VHPDET of graph 564 shown in FIG. 5 usedto indicate removal R of the plug, or indicating that the plug ispresent P. The detect contact HDC or signal VHPDET can be an input (suchas at input IN2) to control unit 130, which can detect whether or notthe detect contact voltage is high or low (e.g. see FIG. 5B), andinstruct phone 100 to behave accordingly. When the signal on the detectcontact is high, the control unit may instruct the phone to route inputand output signals to built-in speaker 108 and microphone 110.Alternatively, when the signal is low, the control unit may instruct thephone to route input and output signals through contacts 124 a-d to theheadset. Circuitry of CPU 130 coupled to IN2 may receive signal VHPDETand determine whether VHPDET is (or transitions to) above or belowthresholds TR and TP.

FIG. 6 also shows early plug removal detection circuit 129 coupled tocontact 124 a to detect transitions of current I on the microphone line.In accordance with embodiments of the invention such transitionsinclude, but are not limited to transitions from a second signal (e.g.S2) indicating that the microphone is disconnected to a third signal(e.g. S4 or S5) indicating that a microphone button is actuated; andfrom a first stable DC level to a third stable DC level through a secondstable DC level different from the first and third levels. Jack contact124 a can be an input (such as at input IND to control unit 130 and/ordetect circuitry 129, which can (1) determine a signal (e.g., voltageand/or current) identifying a transition indicating removal of a headsetplug from a jack, and (2) instruct phone 100 to behave accordingly (e.g.to ignore the signal incorrectly indicating that the microphone buttonis actuated).

For example, control unit 130 and/or circuit 129 could be used to detectwhether or not signal I is at (or has transitioned to or from) signallevel S1, S2, S3, S4 or S5 by comparing current I with the currentthresholds (e.g., TL and/or TU of graphs 462 and 562). If the current Ionly transitions from below to above threshold TU, it may be detectedthat a transition from S1 to S3, S4 or S5 has occurred. Alternatively,if the current I only transitions from above to below threshold TL, itmay be detected that a transition from S1 to S2 has occurred. Also, ifthe current I transitions from below TL to above TU, it may be detectedthat a transition from S2 to S4 or S5 has occurred. Next, if the currentI transitions from above TU to below TL, it may be detected that atransition from S4 or S5 to S2 has occurred. Other transitions betweensignal level S1, S2, S3, S4 or S5 may be similarly detected.

FIG. 6 shows circuitry 132-139 interposed between control unit 130 andcontact 124 a. Circuitry 132-139 includes comparators 135 and 139;balance resistors or circuitry 132, 133, 137 and 138; and pull-upresistor 134 (e.g., one or more bias resistors). FIG. 6 also showscurrent I biased or partially controlled by Voltage Vmicbias 136 andresistor 134 to be output to contact 124 a. Voltage Vmicbias may bevoltage received at contact M of plug 114 and used to bias microphone120. For example, when voltage Vmicbias is applied to contact 124 a,signal I of graph 462 and/or 562 may result, as described herein.

Specifically, CPU 130 is coupled to circuitry 129 at N1 and IN3 todetermine whether signal I transitions from above to below, ortransitions from below to above threshold TU and/or threshold TL.Threshold levels TU and TL can be set by selecting values for resistors132, 133, 134, 137 and 138; and the voltage bias value for power 136.Thus TL can be set so that the output of comparator 135 switches from ahigh to a low signal when signal I transitions from S1 to S2 (or isbelow TL). TU can also be set, so that the output of comparator 139switches from a low to a high signal when signal I transition from S2 toS3, S4 or S5 (or is above TU). CPU 130 may interpret transitions to orfrom level of S2 as indicating removal of the plug from the jack,distinguishing these transitions from the signal level transition fromS1 to S3 without a transition through level S2, in which case there isno switch in the signal at IN1, which stays high. Maintaining this highsignal excludes signal level transition from S1 to S2 and/or from S2 toS4 or S5 (prior to transition from S1 to S3), allowing detection of atransition from below to above TU at IN3 to indicate actuation of themicrophone button, without plug removal.

In some cases, VHPDET level VR may be supplied by a bias voltage ofapproximately 3 volts, and a resistor or resistor network may have avalue such that a bias current is provided during period present P ofapproximately 2 mA (milli-Amperes). Here, threshold TP and/or TR may beapproximately 1 and 2 (or 1.5) volts. Also, according to embodiments,the power supplied at power 136 may be approximately 2 volts or 2.7volts; and resistor 134 may be approximately 2.21 K Ohms. Here,threshold TL may be approximately 0.33, 0.5 or 0.66 mA; and threshold TUmay be approximately 1.33, 1.5 or 1.66 mA. In some embodiments, signal I(e.g., Vmicbias minus Vdrop due to microphone, button, or speaker(s) ofthe headset) may be compared to a threshold TL and TU to provide theoutput of comparator 135 and 139 to inputs IN1 and IN3 respectively. Forexample, where power 136 is 2 or 2.7 volts, Vdrop to cause comparator135 to switch from high to low may represent approximately 1.5 volts,and Vdrop to cause comparator 139 to switch from high to low mayrepresent approximately 1.8 volts. These values may differ, based uponvarious microphone audio signal and button detection circuitry. In somecases the microphone bias voltage may be lower when modulated ornon-stable DC frequencies are being used to indicate multiple buttonactuations of the headset to the telephony device.

According to embodiments, signal levels S1, S2, S3, S4, S5, VP, and VRmay be described as stable direct current (DC) levels, such as theoutput signal of an input passed through a low pass filter, such as afilter that only passes signals below 10, 100, 200, 500 or 1,000 Hz.Similarly, a stable DC level may describe a signal output by comparators135 and 139 (or circuitry 129) as shown in FIG. 6.

It can be appreciated that other designs for circuitry that provide theabove noted detections and/or distinctions of transitions of signal Ibetween signals S1-S5, can be used in place of circuitry 129. Similarly,other designs for circuitry that provide the above noted detectionsand/or distinctions of transitions of signal VHPDET between signals VRand VP, can be used in place of circuitry 149.

FIG. 7 shows some embodiments of an example of a flow diagram of aprocess for distinguishing between receiving a signal transitionindicating actuation of a microphone button, and a transition indicatingremoval of the headset plug from the jack. FIG. 7 shows process 700which may embody a process from embodiments described for FIGS. 1-6.

Process 700 starts with block 710 where, during a telephone call, afirst signal on a microphone line of a headset jack is detected, thesignal indicating that a microphone button is not actuated. Block 710may correspond to detecting signal S1. After block 710 processingcontinues to block 720.

At block 720 a transition is detected on the microphone line, from asecond signal indicating that the microphone is disconnected, to a thirdsignal indicating that the microphone button is actuated. Block 720 mayoccur while the headset plug is being disconnected from the device jack.For example, block 720 may include detecting that signal I transitionsfrom signal S2 to S4 or S5 (e.g., see time T3 or T5 of FIG. 5).

It is considered that block 720 may also include detecting transitionfrom signal S1 to signal S2 (e.g., see time T1 of FIG. 5). Moreover,block 720 may include detecting both transitions from S2 to S4 and fromS2 to S5. Also, block 720 may include detecting transitions from S4 toS2 and subsequently from S5 to S2 (e.g., see time T4 and/or T6 of FIG.5). In some cases, block 720 may also include detecting the transitionsabove on the microphone line while continuing to detect signal VHPDETindicating the headphone is present P (e.g., not detecting thetransition at time TR indicating that the headphone is removed R).

After block 720, process 700 continues to block 730 where the thirdsignal is ignored, thereby maintaining the telephone call. Block 730 mayinclude interpreting signal I as disconnection of the headset from theplug. Block 730 may describe not misinterpreting a button actuation; ordistinguishing between signal I transmissions resulting from actuationof a microphone button and removal of the headset plug from the jack.Block 730 may include ignoring signal S4 or S5; or that signal I beganat S1 and eventually transitioned to S4 or S5.

Block 740 describes detecting removal of the headset plug for the jackafter detecting the transition of block 720. Block 740 may includedetecting the transition if VHPDET at time TR, after detecting thatsignal I began at S1 and eventually transitioned to S4 or S5.

FIG. 8 shows additional embodiments of an example of a flow diagram of aprocess for distinguishing between receiving a signal transitionindicating actuation of a microphone button, and a transition indicatingremoval of the headset plug from the jack. FIG. 8 shows process 800which may embody a process from embodiments described for FIGS. 1-6.

Process 800 starts with block 810 by detecting on a microphone line of aheadset jack during an ongoing call, that the microphone line hastransitioned from a first stable DC level to a third stable DC signallevel indicating a user's actuation of a switch in a connected headset.Block 810 may include detecting signal I transitioning from S1 to S3 asdescribed for FIG. 4, such as by detecting that signal I has nottransitioned across threshold TL.

After block 810, process 800 continues to block 820. At block 820 it isdetermined whether the transition occurred through a second stable DClevel different than the first and third levels, such as a second levelthat is not between the first and third levels. Block 820 may includedetecting whether signal I transitions across threshold TL.

Block 820 may include detecting that the transition through a secondstable DC level includes one or more transitions between the secondlevel and the third level, as described above for block 720. The secondstable DC level may have an amplitude that is below an amplitude ofcurrent for the first signal and for the third signal.

If at block 820 the transition is not through a second stable DC level,process 800 continues to block 830 where an ongoing call is hung up ordisconnected. Block 830 may include the device that performs blocks 810and 820 causing the call to be hung up or disconnected by disconnectingthe call at that device. Also, block 830 may include detecting thetransition shown in FIG. 4 indicating that the microphone button hasbeen actuated, thus determining that it is the users desire todisconnect the call.

If the transition is not through a second level at block 820 processingcontinues to block 840 to ignore the signal indicating that themicrophone button is actuated; or to maintain a telephone call afterreceiving the signal indicating that the microphone button is actuated.Block 840 may include detecting that signal I has transitioned from S1to S2; or from S2 to S4 or S5.

After block 840, process 800 continues to block 850 where removal of theheadset plug from the jack is detected after detecting the transition ofblock 810. Block 850 may include descriptions above for block 740. Block850 might also include detecting removal of the headset plug from thejack, after ignoring the third stable DC level as described for block840. In some case, block 850 includes ignoring the third stable DCsignal level, and maintaining a telephone call, after detecting thetransition at block 810.

In some embodiments, in place of maintaining the telephone call inblocks 730 and/or 840, other actions or behaviors controlled by button121 may be caused or ignored (e.g., not taken). For example, some phoneswill play music if a call is not in progress and the microphone buttonin actuated. In this case, ignoring the signal in those blocks may causemusic to not start playing, although the music would have startedplaying if a single click of the headset button were detected. Since thesignal is ignored, the music is not played.

In some embodiments, some or all of the blocks process 700 and/or 800are caused by circuit 129, control unit 130, and/or circuitry 149. Inaddition, some or all of the blocks may describe controlling behavior ofphone 100. Also, some or all of the blocks may be performed by atelephony device including call management circuitry (e.g., includingcircuit 129), such as to detect the transitions of signal Iindependently of a plug detect circuit (e.g., circuit 149) detectingremoval of the plug from the jack. The telephony device may also includea balance circuit coupled to the call circuit to cause the call circuitto detect transitions between the second stable level and the thirdstable level, such as described above. Such balance circuitry mayinclude resistors 137 and 138.

Next, headset 116 may be any component that can be coupled to and usedin conjunction with phone 100, such as a headset including audiospeakers, earphones, headphones, noise cancellation, a video display,microphone, or combinations of functionality thereof. The electroniccoupling between signal contact 124 a and contact M may be a wired orwireless electronic connection or attachment. For example, a wirelesstransmission system may exist between contact 124 a and contact M, suchas a transmission system transmitting audio signals, current, andvoltage levels described herein.

Phone 100 may be specially constructed for the purposes describedherein, or it may comprise or be part of a computer (e.g., portable,such as a laptop or hand held computer; or stationary, such as a desktopcomputer), portable device, telephone or cellular telephone speciallyconfigured by a computer program stored in a storage medium. Such acomputer program (e.g., program instructions) may be stored in a machine(e.g. computer) readable non-volatile storage medium or memory, such as,a type of disk including floppy disks, optical disks, CD-ROMs, andmagnetic-optical disks, read-only memories (ROMs), erasable programmableROMs (EPROMs), electrically erasable programmable ROMs (EEPROMs),magnetic or optical cards, magnetic disk storage media, optical storagemedia, flash memory devices, or any type of media suitable for storingelectronic instructions. Phone 100 may also include a processor coupledto the storage medium to execute the stored instructions. The processormay also be coupled to a volatile memory (e.g., RAM) into which theinstructions are loaded from the storage memory (e.g., non-volatilememory) during execution by the processor. The processor and memory(s)may be coupled to circuitry 129, circuitry 149, and/or control unit 130.In some cases, the processor may include control unit 130.

At least certain embodiments of phone 100 may be part of a portabledevice, telephone or cellular telephone, which may include a mediaprocessing system to present the media, a storage device to store themedia and may further include a radio frequency (RF) transceiver (e.g.,an RF transceiver for a cellular telephone) coupled with an antennasystem and the media processing system, computer, portable device,telephone or cellular telephone. In certain embodiments, media stored ona remote storage device may be transmitted to the media player throughthe RF transceiver. The media may be, for example, one or more of musicor other audio, still pictures, or motion pictures. For example, theseembodiments may be part of a mobile telephone which includes thefunctionality of one or more: media players (music and/or video media),entertainment systems, personal digital assistants (PDAs), generalpurpose computer systems, portable device, Internet capable portabledevice, special purpose computer systems, an embedded device withinanother device, or other types of data processing systems or devices(e.g., an iPhone® from Apple Inc. of Cupertino, Calif.).

The processes, instructions, and/or circuitry described herein may bedesigned and/or sold by handset manufacturers, such as manufacturers ofa “source device” that can distinguish between microphone line (e.g.,microphone contact) signal transitions resulting from (1) actuation of amicrophone button of a headset plugged into a device jack, and (2)removal of the headset plug from the jack.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

What is claimed is:
 1. A method for operating a telephony device havinga headset jack to connect with a headset plug of a headset, the headsethaving a microphone and a microphone button, comprising: during atelephone call, detecting a first signal on a microphone line of theheadset jack, with the microphone connected thereto, wherein the firstsignal indicates that the microphone button is not actuated; and thenwhile the headset plug is being disconnected from the jack, detecting asecond signal indicating that the microphone is disconnected, and athird signal indicating that the microphone button is actuated.
 2. Themethod of claim 1, further comprising detecting removal of the headsetplug from the jack, after detecting transition.
 3. The method of claim1, wherein the transition on the microphone line is detected withoutfirst having detecting removal of the headset plug.
 4. The method ofclaim 1, wherein detecting the transition further comprises detecting aplurality of transitions from a plurality of the second signals, to aplurality of the third signals.
 5. The method of claim 4, whereindetecting the transition further comprises detecting a plurality oftransitions from the third signal back to the second signal, afterdetecting each transition from the second signal to the third signal. 6.The method of claim 5, wherein the second signal is a signal indicatingan open circuit, and wherein the third signal is a signal that indicatesa substantially lower impedance path than path on the microphone linewhen detecting the first signal.
 7. The method of claim 1, wherein thetransition comprises one of a transition from a lower current signal toa higher current signal, a transition from a signal indicating an opencircuit to a signal that indicates a substantially lower impedance paththan a path on the microphone line when detecting the first signal. 8.The method of claim 1, wherein an amplitude of the second signal is notbetween an amplitude of the first signal and an amplitude of the thirdsignal.
 9. The method of claim 8, wherein the amplitude of the secondsignal is below the amplitude of the first signal and is below theamplitude of the third signal.
 10. The method of claim 1, wherein thefirst and second signals occur within a specified time.
 11. A telephonydevice comprising: a headset jack to receive a headset plug of aheadset; and a call management circuit coupled to the jack, the callmanagement circuit to detect a signal on a microphone line of theheadset jack during an ongoing call; the call management circuit to hangup the call in response to detecting that the microphone line hastransitioned from a first stable DC level to a third stable DC levelindicating a user's actuation of a switch in a connected headset, andfurther operative to detect a second stable DC level that is differentthan the first and third levels.
 12. The apparatus of claim 11, furthercomprising a plug detect circuit coupled to the jack to detect removalof the headset plug from the jack, wherein the call circuit can detectthe transition independently of the plug detect circuit detectingremoval of the plug from the jack.
 13. The apparatus of claim 11,further comprising a balance circuit coupled to the call circuit tocause the call circuit to detect a plurality of transitions from aplurality of the second stable DC levels, to a plurality of the thirdstable DC levels.
 14. The apparatus of claim 13, wherein the balancecircuit is to cause the call circuit to detect a plurality oftransitions from the third signal back to the second signal, afterdetecting each transition from the second signal to the third signal.15. The apparatus of claim 14, wherein the second signal is a signalindicating an open circuit; and wherein the third signal is a signalthat indicates a substantially lower impedance path than a path on themicrophone line when detecting the first signal.
 16. The apparatus ofclaim 11, wherein in response to detecting that the microphone line hastransitioned from the first DC level to the third DC level is through asecond stable DC level, the call circuit one of ignores the signal levelindicating the user's actuation of the switch, maintains a telephonecall after detecting the transition, and causes music not to startplaying after detecting the transition.
 17. A telephone devicecomprising: a headset jack to receive a plug of a headset; and a callmanagement circuit coupled to the jack, the call management circuit todetect a signal on a microphone line of the headset jack during anongoing call, the call management circuit to: during a telephone call,detect a first signal on a microphone line of the headset jack, with themicrophone line connected thereto, wherein the first signal indicatesthat the microphone button is not actuated; and then while the headsetplug is being disconnected from the jack, detect a second signalindicating that the microphone is disconnected, and a third signalindicating that the microphone button is actuated.
 18. A method foroperating a telephony device having a headset jack to connect with aheadset plug of a headset, the headset having a microphone and amicrophone button, comprising: detecting, during an ongoing call, thatthe microphone line has transitioned from a first stable signal level toa second stable signal level indicating actuation of a switch in aconnected headset; and in response thereto, changing an activation stateof a microphone.